Gas analysis



Jan. 28, 1941. L. QR-v"; 2,414,876

GAS ANALYSIS Filed larch 10. 1941 i 7 Refrigerant munome'er T? lo lnlet for I I Gus iobeomlyzed mam I ATTORNE' Y Patented Jan. 28, 1947' GAS ANALYSIS Leo Horvltz, Houston, Tex, assignor to Esme E.

Bosairc, Houston, Tex.

Application March 10, 1941, Serial lilo. 382,607 5 Claims. (0113 -232) The present invention relates to gas analysis and has particular applicationto a geochemical prospecting method in which soil gases are end of the chamber 20 is a, suitable filament 2i adapted to be heated electrically.

analyzed for minute traces of hydrocarbons, es-

pecially those heavier than methane.

An object of the present invention is to pro- I V vide a unique system for'controlling the move- 1 meat of gas undergoing analysis in' the analytical apparatus.

, An additional object of the present invention is to eflect the movement of gases into combustion tubes and from such tubes to measuring means by subjecting the various parts of the ap-,

paratus in sequence to suitable refrigerants.

Further objects and advantages of the present invention will appear from the following detailed description of the accompanying drawing in which the single figure isa front elevation in diagrammatic form of one type of apparatus suitable for carryingout the method of the present invention. l

Line I! is provided with mercury valve 4 between which and the trap 8 is a branch line 22 which is connected through valve I to a McLeod gauge 23. The gas to be analyzed isusually prepared for analysis before being introduced into the system in accordance with the teachings of my co-pending applications Serial Nos. 183,960, filed January 8, 1938, now U. 8. Patent No. 2,287,101, 369,213, filed December 9. 1940,

and 369,124, filed December 9, 1940. Briefly, this preparation involves the removal of carbon dioxide and water from the gas to be analyzed. In the preferred method of geochemical prospecting to which the present invention isparticularly Referring to the drawing in detail, numeral I designates an inlet for the gas to be analyzed.

In this system there are used mercury float valves which are described in more detailin my copending application Serial No. 183,960, filed January 8, 1938, now U. 8. Patent No. 2,287,101, a

and are designated herein by numerals 2, 8, I, 5, 6, and'l.

The inlet i is connected through valve 2 to a trap 8 which is preferably of. the type shown in U. S. Patent 2,177,139,issuedOctober 24, 1939. This trap is adapted to be immersed in a'suitable refrigerant carried by a vessel 9 which will usually be removably arranged around the trap. The outlet of the trap is connected through valve 1 to a pump. Between valve 3 and the trap is a branch line ID to which is connected a manometer .H and which is connected through valves I and 6 to an inlet 12 for air or oxygen. Between valves 5 and G is a branch line II, which is connected through a trap ll similar in construction to trap 0, and similarly capable of be-- ing immersed in a refrigerant carried by a vessel it, The other end or the trap is, connected through a valve "to a combustion chamberii in which is a filament i0 adapted to be heated electrically.

Between valve 2 and trap 8 is a branch line I! which empties into a chamber 20 which, aswill be seen, is of peculiar construction, having. in effect, an invertedpear. shape. The stem end of the pear is adapted to be immersed in a refrigerant carried by a receptaclepsuch as that designated by numeral 0. Arranged in the large I whereby any combustible impurities in the airsoil'samples, systematically collected over an area;

to be explored, preferably at a uniform depth in excess of about 4 feet, or from different depths of a well undergoing drilling, to a desorbing action, usually through the agency of heat and vacuum, preferably accompanied by a simultaneous treatment with an inorganic acid, such as hydrochloric acid or phosphoric acid.

Before the gas to be analyzed is introduced into the system, the trap 8, the chamber 20, and the McLeod gauge are all evacuated by application of suction by the pump with valves 3, l, and 1 open, and the remaining valves closed. After the evacuation, valves 3, 4, and l are closed, leaving the various units mentioned in evacuatedcondition. It is also desirable to prepare a batch of purified air or oxygen to be used in the combustion step. This is accomplished by opening is built up in this system, the valve 8 is closed.

During the admission of this air the trap ll is partially immersed, as illustrated, in a suitable refrigerant," such as liquid nitrogen. This condenses out, in the trap ll, all the carbon dioxide andwater vapor and any heavier hydrocarbons,

, for example which may be in the air. The valve I8 is then closed and the filament I8 is heated,

or oxygen in the bulb I! are burned. With valve it closed, valve 0 is opened, the refrigerant is removed from the trap, and suction is applied to line i2 whereby any condensibles collected in trap H are removed from the, system, leaving the space between valve i8 and valves 6 and 0 respectively in evacuated condition. Valve 0 valve 4 is opened and the line I2.

The system then stands with all the valves closed with trap 8, chamber 20, and McLeod gauge in evacuated condition and with a purified sample of air or oxygen in bulb IT. The valve 2 is then opened and the gas to be analyzed is introduced through inlet I until the manometer il registers about 20 millimeters, while trap 8 is immersed in a suitable refrigerant, such as liquid nitrogen, in receptacle 9. This results in the condensation and collection in trap 8 of constituents such as ethane and heavier hydrocarbons, the methane and air in the gas remaining uncondensed. Valve 2 is then closed, and valve 3 is opened and all uncondensed gas is pumped out of the system.

Valve 3 is then closed and the receptacle 8 is removed from the trap 8, whereupon the condensed constituents vaporize and become gaseous. If desired, valve 1 can then be opened and the volume of these constituents measured by the McLeod gauge. This measurement serves a useful purpose.in connection with subsequent measurements in ascertaining the hydrocarbon components of the gas. If this volume is measuredat this point the receptacle 9 is again applied to trap 8 in order to cause the condensibles to flow from the McLeod gauge to the trap, where they are again collected. Of course, if the volume-measuring step is not employed, this repeated trapping is not necessary. After the volume is measured and the condensibles are again collected in trap 8 valve 1 is closed and receptacle 9 is again removed from trap 8. The same receptacle 9 or a similar receptacle containing a suitable re-.

frigerant, such as liquid nitrogen, is then applied to the small end of the chamber 20. The removal of'the receptacle from the trap 8 causes the condensed constituents to vaporize and the application of the refrigerant to the bottom of chamber 20 causes these vapors or gases to flow into chamber 20, where the condensibles are again condensed.

At this point refrigerant is again applied to trap I4 and valves 5 and I 6 are opened, whereby the gas from bulb I1 is permitted to pass into the chamber 20. In its passage through refrigerated trap l4, any products of combustion contained in this gas are condensed and removed. The amount of air or oxygen admitted is indicated on the manometer H and this will usually be an amount suflicient to raise the pressure in the system to about 25 millimeters. When this pressure is attained, valve l is closed, the refrigerant is removed from the lower end of chamber 20, and the filament 2| is heated, whereby the vaporized constituents in chamber 20 are burned. After the burning is completed, which will usually take place in rection, with the result that the products of combustion, namely, carbon dioxide and water, are condensed and collected in trap 8. This operation will ordinarily take not morethan a minute and, at its conclusion, the valve 3 is opened and suction is applied to the system to withdraw all non-condensed gases from the trap 8, the li H, and the chamber 20.

i and the various tion are purely illustrative.

At the end of the pumping step, which will ordinarily be complete in about 3 or 4 minutes depending upon the type of pump used,

the valves 3 and 4 are closed, the refrigerant is removed from trap 8, and

the vaporized cons to the McLeod the volume of gauge, the line 22,

lines between the trap and valve 1 is opened, permitting tituents to move from trap 8 gauge. It will be understood that the system,

including the McLeod I9, the trap, and the valve 3 and valve 5 the line is known. With this volume fixed, the reading of the McLeod gauge may be of the carbon dioxide and the combustion in taken as a measure water produced by chamber 20. If desired, the

liquid nitrogen around the trap 8 can be replaced by a refrigerant which will ture such that only carbon maintain a temperadioxlde will vaporize out of the trap. In this connection, it may be noted that the system at this point is at an extremely low pressure, usually only a fraction of a millimeter whereby, in the absence of a refrigholding the water erant, water will also vaporize. A Dry Ice acetone bath is a suitable refrigerant mit the vaporization of carbon which will perdioxide while in a condensed state. When this operation is adopted, the reading on the McLeod gauge indicates only the quantity of carbon dioxide produced by the combustion.

Then, of course, by removing the second refrigerant fromthe trap andmaking another reading of the McLeod gau ge, the amount of water produced can be determined by difference.

Referring these readings to those taken before burning enables the operator to determine the carbon-hydrogen ratio, thereby giving information as to the nature of the hydrocarbons. This,

together with the choice of suitable temperatures of previous fractionation of the gas can be made to give information It will be observed as specific as desired.

ment of the gas undergoing anlysis from one portion of the apparatus to another is effected by making a cold spot desired to move the out of the point to which it is gas. This simplifies the system considerably and makes for a rapid, accurate operation. The constituents to be determined are present inthe gases ordinarily analyzed in this apparatus in amou per million to perh million. The accur paratus may be ment that it will nts ranging from a few parts aps several hundred parts per acy and sensitivity of this apbest characterized by the statemeasure down to one part of the significant constituents per million parts of gas.

It will be underst val constituents heavie 00d that the apparatus shown ues given the specific descrip- For example, when r than ethane are sought different refrigerants will be employed. The operating times for the various steps may vary with different gases, different refrigerants, different vacuum pumps. and different sizes of apparatus. All these details are given here merely to describe a complete operation.

The nature and 0 having been thus d is claimed as new and secured by Letters Patent 1. In the method bustible constituents ucts of biects of the present invention escribed and illustrated. what useful and is desired to be of gas analysisin which comare burned and the prodthat in this system the m0ve-' the apparatus by successively moving said cold spot to said diflerent parts of the apparatus.

2. A method for analyzing a gas for its content of combustible material present therein in minute amounts which comprises introducingsald gas into a closed system including a condensation zone and a combustion zone, refrigerating said condensating zone to a temperature sufficiently low to effect the condensation of the combustible constituents, withdrawing the residual 'gasfrom the system, withdrawing the refrigerant from the condensation zone and applying a refrigerant to the combustion zone whereby the condensed constituents are caused to vaporize and travel to the combustion zone, thereafter withdrawing the reirigerant from the combustion zone, burning the combustible constituents and V measuring the gas into a closed system including a condensation.

zone and a combustion zone, applying refrigeration to the condensation zone to effect the condensation therein of the combustible constituents of said gas, withdrawing the residual gas from the system, withdrawing the refrigerant from the condensation zone and applying a refrigerant to the combustion zone whereby said condensed constituents are caused to vaporize out of said condensation zone and travel tosaid combustion zone where they are again condensed, withdraw- ,ing the refrigerant from the combustion zone, burning the combustible constituents, again applying a refrigerant to the condensation none whereby theproducts of combustion are caused to travel to said condensation zone and condensed therein, withdrawing the residual gas from. the system, and measuring the quantity of the products of combustion. V

4. A method according to claim 3 in which the closed system is evacuated before the introduc tiontherein of the gasto be analyzed.

5. A method for analyzing a gas for combustible constituents present therein in minute amounts which comprises introducing the gas into a closed evacuated system including a condensation zone and a combustion zone, applying a refrigerant to ,the condensation zone to effect the condensation therein or the combustible constituents contained in said gas, removing the residual gas from the system, withdrawing the refrigerant from the condensation zone whereby the condensed con.

,stituents are vaporized, measuring the resulting pressure in the system as a measure of the quan tity of said condensed constituents, applying a refrigerant to the combustion zone, thereby causing said constituents to condense in said zone, introducing a combustion supporting gas into said zone, withdrawing the refrigerant from said conn bustion zone whereby the said condensed corrstituents are vaporized, 'burning said constituents, applying a refrigerant to the condensation zone whereby the products of combustion are caused to condense therein, removing the residual gas -from the system, and determining the quantity 'ol the condensed combustion products.

LEO HORVJTJL2. 

